Journal articles: 'Two-point loading'

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Sangeetha, Palanivelu, S. Ramana Gopal, A. Jai Vigneshwar, K. Vaishnavi, and A. Srinidhi. "Flexural Strength of Steel-Concrete Composite Beams Under Two-Point Loading." Civil and Environmental Engineering Reports 30, no. 4 (December 1, 2020): 21–32. http://dx.doi.org/10.2478/ceer-2020-0047.

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Abstract This study investigates the flexural strength of simply-supported steel–concrete composite beams under two-point loading. A total of four specimens were tested to failure for varying parameters including type of connectors (stud and channel) and number of connectors (two and four). ANSYS software was used to establish the finite element models that can simulate the flexural behaviour of the composite beam. The test results show that a beam with channel connectors performs better than a beam with stud connectors. The composite beam with two connectors between the beam and slab causes additional deflection due to slippage in the connectors, when compared to the beam with four connectors. The results from the analytical model are in good agreement with the experimental results.

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Langley, R. S. "THE RESPONSE OF TWO-DIMENSIONAL PERIODIC STRUCTURES TO IMPULSIVE POINT LOADING." Journal of Sound and Vibration 201, no. 2 (March 1997): 235–53. http://dx.doi.org/10.1006/jsvi.1996.0744.

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Hanson, M. T. "Elastic Fields Resulting From Concentrated Loading on a Three-Dimensional Incompressible Wedge." Journal of Applied Mechanics 62, no. 3 (September 1, 1995): 557–65. http://dx.doi.org/10.1115/1.2895981.

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This paper considers point force or point moment loading applied to the surface of a three-dimensional wedge. The wedge is two-dimensional in geometry but the loading may vary in a direction parallel to the wedge apex, thus creating a three-dimensional problem within the realm of linear elasticity. The wedge is homogeneous, isotropic, and the assumption of incompressibility is taken in order for solutions to be obtained. The loading cases considered presently are as follows: point normal loading on the wedge face, point moment loading on the wedge face, and an arbitrarily directed force or moment applied at a point on the apex of the wedge. The solutions given here are closed-form expressions. For point force or point moment loading on the wedge face, the elastic field is given in terms of a single integral containing associated Legendre functions. When the point force or moment is at the wedge tip, closed-form (nonintegral) expressions are obtained in terms of elementary functions. An interesting result of the present research indicates that the wedge paradox in two-dimensional elasticity also exists in the three-dimensional case for a concentrated moment at the wedge apex applied in one direction, but that it does not exist for a moment applied in the other two directions.

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Quadri, Ajibola Ibrahim. "Strut and Tie Modelling of Reinforced Concrete Deep Beams Under Static and Fixed Pulsating Loading." Al-Nahrain Journal for Engineering Sciences 23, no. 3 (November 24, 2020): 306–12. http://dx.doi.org/10.29194/njes.23030306.

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Numerical analysis of the performance of reinforced concrete (RC) deep beam subjected to static and fixed-point pulsating loading at the midpoint has been investigated. Three-dimensional nonlinear finite element model using the Strut and Tie approach was adopted. The damage level under the influence of the applied fixed pulsating loading is higher than the static applied loading, hence early crack was observed because of the stepwise loading in the form of vibration. Although the Strut and Tie approach gave a good estimation of the resistance capacity of the beam, the beam undergo high shear damage when subjected to these two types of loading. Material strength properties, applied loadings and cross-sections adopted are some of the factors that affect the performance of the deep beam.

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Wu, X. F., Y. A. Dzenis, and W. S. Zou. "Interfacial edge crack between two bonded dissimilar orthotropic strips under antiplane point loading." ZAMM 83, no. 6 (June 20, 2003): 419–22. http://dx.doi.org/10.1002/zamm.200310063.

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Kochergin, Victor, Igor Maksimov, Victor Pevzner, and Evgeniya Polunina. "Track loading on Russian Railways under modern maintenance conditions." E3S Web of Conferences 135 (2019): 02002. http://dx.doi.org/10.1051/e3sconf/201913502002.

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Rail fasteners loading and its influence on the track deformability under modern maintenance conditions with increased cars axle loads is observed. The difference between oneand two-point wheelrail contact loading scheme is shown. The authors present the analysis of domestic and foreign methods of pads bench tests and show the necessity of carrying out tests imitating real (two-point contact) loading of pads. The bench test method for researching fastener loading and pad strain characteristics in a wide range of vertical and lateral loads under two-point contact scheme based on a number of field tests is presented. The results of static tests and following dynamic ones with cycling loading, which were carried out on a two-sleepers bench, are observed. Bench tests carried out by VNIIZHT and the analysis of the cyclic test methods showed the importance of fasteners tests with a real loading simulation making it possible to explain the causes of track gauge widening and decrease of track inclination, which considerably influences track stability and wear of the track and rolling stock.

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Meynendonckx, J., G. Heuvelmans, B. Muys, and J. Feyen. "Effects of watershed and riparian zone characteristics on nutrient concentrations in the River Scheldt Basin." Hydrology and Earth System Sciences Discussions 3, no. 3 (May 2, 2006): 653–79. http://dx.doi.org/10.5194/hessd-3-653-2006.

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Abstract. The relative influence of a set of watershed characteristics on surface water nutrient concentrations was examined in 173 watersheds within two subcatchments (Upper-Scheldt and Nete) of the River Scheldt Basin (Flanders, Belgium). Each watershed was described by seasonal rainfall, discharge loading of point sources, morphological characteristics (area, average slope, drainage density, elongation), land use and soil properties (soil texture and drainage). Partial regression analysis revealed that soil drainage variables had the strongest influence on nutrient concentrations. Additional influence was exerted by land use and point source loading variables. Nitrate concentrations were positively correlated with effluent loadings coming from wastewater treatment plants and with the area of agricultural land. Phosphate concentrations were best explained by effluent loadings of industrial point sources and by the area of urban land. Land use close to the river was not a better predictor of nitrate and phosphate concentrations than land use away from the river. This suggests that the mediating impact of riparian zones is rather explained by the hydrologic pathways within the buffer strip.

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Meynendonckx, J., G. Heuvelmans, B. Muys, and J. Feyen. "Effects of watershed and riparian zone characteristics on nutrient concentrations in the River Scheldt Basin." Hydrology and Earth System Sciences 10, no. 6 (November 28, 2006): 913–22. http://dx.doi.org/10.5194/hess-10-913-2006.

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Abstract. The relative influence of a set of watershed characteristics on surface water nutrient concentrations was examined in 173 watersheds within two subcatchments (Upper-Scheldt and Nete) of the River Scheldt Basin (Flanders, Belgium). Each watershed was described by seasonal rainfall, discharge loading of point sources, morphological characteristics (area, average slope, drainage density, elongation), land use and soil properties (soil texture and drainage). Partial regression analysis revealed that soil drainage variables had the strongest influence on nutrient concentrations. Additional influence was exerted by land use and point source loading variables. Nitrate concentrations were positively correlated with effluent loadings coming from wastewater treatment plants and with the area of agricultural land. Phosphate concentrations were best explained by effluent loadings of industrial point sources and by the area of urban land. Land use close to the river was not a better predictor of nitrate and phosphate concentrations than land use away from the river. This suggests that the mediating impact of riparian zones is rather explained by the hydrologic pathways within the buffer strip.

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Morshed, M. M. Maruf, Anthony C. Zander, and Colin H. Hansen. "Two-Dimensional and Three-Dimensional Acoustic Loading on Cylinders Due to a Point source." AIAA Journal 49, no. 11 (November 2011): 2421–29. http://dx.doi.org/10.2514/1.j050749.

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He, Ran, Xing Ping Shu, and Bo Wang Chen. "Test on Eccentricaly Loaded Four-Tube Concrete-Filled Steel Tubular (CFST) Laced Columns of No Yield Point." Applied Mechanics and Materials 204-208 (October 2012): 4658–63. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.4658.

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In order to study the characteristics about deformation and stress of four-tube concrete-filled steel tubular(CFST) laced columns of no yield point, a test with the parameter of eccentricity on two our-tube concrete-filled steel tubular(CFST) laced columns of no yield point has been finished by means of 500t press. The results of the test shows that the larger the eccentricity, the more obvious the global deformation of laced columns tends to become, and the four-tube CFST laced columns of no yield point under eccentric compression were subjected to overall bending failure and ductile failure with obvious premonition; In the meanwhile, confinement effect of main tubes away from the loading point of laced columns under eccentric compression was inapparent , while confinement effect of the two main tubes close to the loading point begain to play and increase before it was to fail, which made the characteristics about deformation and stress of the the two main tubes close to the loading point similar to the single CFST column under axial compression.

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Almaskari, Fahad, and Farrukh Hafeez. "Study on behaviour of geometrically scaled glass reinforced epoxy tubes subjected to non-coincident quasi static-indentation." International Journal of Structural Integrity 9, no. 5 (October 1, 2018): 675–92. http://dx.doi.org/10.1108/ijsi-12-2017-0078.

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Purpose The purpose of this paper is to study the behaviour of glass reinforced epoxy tubes subjected to repeated indentation loads at two non-coincident indentations 180° apart. Design/methodology/approach Four geometrically scaled specimens ranging from 100 to 400 mm diameter were used in repeated indentation tests. Force, displacement and damage growth were recorded for loading and unloading until the indenter returned to its original starting point. Findings Similar scaled trends were observed between the non-coincidental loadings. Unlike reported response form coincidental loadings, the responses from non-coincidental loadings yield lower values for bending stiffness and peak load. Research limitations/implications The differences in behaviour of the specimen between non-coincident loadings were attributed to reductions in fracture toughness and circumferential modulus. Practical implications Distant non-interacting damage and delamination around the circumference does reduce the structural performance. Originality/value Behaviour of composite tubes under different loading conditions, for example low speed impact or quasi static indentation, is widely studied, however little attention has been given to the repeated loading incidents.

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Jennings, Eleanor, Norman Allott, David Lenihan, Bill Quirke, David Taylor, and Helena Twomey. "Drivers of long-term trends and seasonal changes in total phosphorus loads to a mesotrophic lake in the west of Ireland." Marine and Freshwater Research 64, no. 5 (2013): 413. http://dx.doi.org/10.1071/mf12166.

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Excess phosphorus (P) loading is a major cause of deterioration in surface water quality. In Ireland, regulation has focussed on control of P losses from agriculture and wastewater treatment plants (WWTPs): the two main sources of excess P. Hindcast modelling for Lough Leane, south-west Ireland, indicated that, while the only municipal (point) source contributed up to 41% of the annual TP loading until the mid 1980s, over 90% of the TP load was from diffuse sources following upgrading of the WWTP. Field data from 2000–2006 confirmed that most of the TP load came from agriculture, with 73% being exported between September and February, generally the wettest months in the region. However, the WWTP contributed up to 60% of daily loads during summer. Short lake residence times (two to four months) between October and February indicated that external loadings during these months were unlikely to make a significant contribution to summer phytoplankton growth in the lake. In contrast, the potential effects of point sources during low flows were maximised by longer residence times between April and September. The results highlight the importance to aquatic pollution impacts of, and therefore the need for regulatory responses to respect, seasonal variations in loading and residence time.

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Deng, Ai Min, Dao Yuan Xu, and Wei Xuan Zhu. "Research on the K_{II C} of the Two Types of Concrete Specimens." Applied Mechanics and Materials 157-158 (February 2012): 1260–63. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.1260.

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According to the mode II fracture test results of the concrete of the double-edge notched specimens with four-point shear loading and half symmetrical loading, the relationship of the mode II fracture toughness of two type of concrete specimens are analyzed. Based on the numerical simulation, the stress field near the crack tip is analyzed by use of the finite element method, and the mode II fracture toughness of the two types of concrete specimens are calculated with the displacement extrapolation method, and the difference with the experimental results are studied. Because of the uniform stress of the specimen with half symmetric loading, and the shear stress in the fracture process zone is much larger than the first principal stress during the entire test process, while the phenomenon of opening and torsion of the surface of cracks may appeared at the four point shear loading conditions, which leads to the fracture process of the specimen is not always the mode II fracture of pure shear.

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Kumar, Sanjay, Anoop Kumar Pandouria, and Vikrant Tiwari. "Evaluation of Load and Load Point Displacement Through Three Point Bend Set up for Dynamic Loading." International Journal of Advance Research and Innovation 4, no. 1 (2016): 239–42. http://dx.doi.org/10.51976/ijari.411634.

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Three point bend set up is used to evaluate load and load point displacement on specimen during dynamic condition. Here, experiments have been conducted on Al 6063 alloys on Modified Hopkinson Pressure Bar (MHPB) in dynamic condition. The cylinder pressure and striker velocity was measured during experiments and it was 3.1 bar and 24m/s respectively. The strain gauges, data acquisition computer were used to measure strain at two points at Hopkinson bar. The load point displacement and load are obtained by the two point strain measurement methods and one dimensional wave theory in terms of strains measured experimentally at two points.

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Montanari, Roberto, and Nadia Ucciardello. "Mechanical Behaviour of Metals under Explosive Loading." Materials Science Forum 638-642 (January 2010): 22–28. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.22.

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The paper briefly examines the metallurgical effects of shock waves on different metals. Two points are then specifically addressed. The first one regards how X-ray diffraction (XRD) can be usefully employed to get exhaustive information about the microstructure of a shock loaded metal. The second point concerns the mechanisms of martensitic transformation in alloys such as AISI 304 when submitted to repeated explosive deformations.

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Konopska-Piechurska, Małgorzata, Wioletta Jackiewicz-Rek, and Paweł Łukowski. "Correlations between compressive strength and tensile strength of concrete for two-layers pavement with exposed aggregate." Budownictwo i Architektura 13, no. 4 (December 9, 2014): 137–44. http://dx.doi.org/10.35784/bud-arch.1751.

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In the paper the results of experiments on concrete pavement with exposed aggregate technology placed in two technological layers were presented. The following properties were measured: compressive strength, flexural strength by two methods: two-point loading and centre-point loading, tensile splitting strength of cubic and cylindrical samples. The study was performed for two type of concrete with a maximum aggregate size Dmax 8 mm (concrete applied to the upper layer of concrete pavement - GWB) and Dmax 22 mm (concrete used for the bottom layer - DWB). After the analysis of the tests, the correlations between compressive strength and tensile strength, measured by flexural strength and tensile splitting strength, were determined for the used two-layers concrete pavement with exposed aggregate depending on applied Dmax.

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R Padma Rani & R Harshani. "Numerical Simulation on Reinforced Concrete Beam with Different Cover Size under Two Point Bending Load." International Journal for Modern Trends in Science and Technology 7, no. 05 (May 6, 2021): 39–43. http://dx.doi.org/10.46501/ijmtst0705005.

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Structural analysis is used to assess the behavior of engineering structures under the application of loads. Usually, structural analysis methods include analytical,experimental and numerical methods is used in thisproject, however, only Analytical method is used and the values are taken from literature reference, to get familiar with Finite Element Analysis (FEA) using ANSYS, this is done to acquire practical knowledge about of the effect of the cover. The aim is to identify different failure modes under a range of loading conditions by changing the cover size to get the data of various parameters such as deflection, stress etc. Study of cover helps to observe the stability, reliability and the overall strength of the structural beam. This project attempts made to study the effect of cover on the behavior of reinforced concrete beam. Forthis analytical study, the Reinforced concrete beam specimen of 2000x100x200mm was considered.ANSYS software is a suite of engineering simulation software, based on finite element method, which can solve problems ranging from linear analysis to nonlinear analysis. The Doubly reinforced beams weremodeled by using geometry. In this model,various covers are provided. The beam specimensused in this study were tested under two-point static loading condition until failure of the specimen. From theobtained resultconcluded that the total deformation and directional deformation values are low in 25mm cover compared to other cases but the equivalent stress value is low in 35mm cover size compared to 25mm cover size.

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Nam, Byeung Gun, H. S. Na, R. Liu, and Katsuhiko Watanabe. "Effect of Electromechanical Loadings on Fracture Strength of Piezoelectric Ceramics." Key Engineering Materials 353-358 (September 2007): 1544–47. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.1544.

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The effect of electromechanical loadings including their sequence, which was motivated by the property of crack energy density for piezoelectric material, was experimentally investigated. Three-point bending fracture test was performed for two piezoelectric ceramics under different electromechanical loading conditions. It was found that the fracture loads under closed circuit condition are greater than those under open circuit condition. Effect of applied electric field on fracture load in the test varied with materials. Applied electric field always enhanced crack extension in C-21 ceramics regardless of their directions, while it produced very little effect on crack extension under negative electric fields in C-2 ceramics. It was also found that electromechanical loading sequence clearly affects fracture strength, although its effect varies also with materials.

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Rondinella, Vincenzo V., and M. John Matthewson. "Effect of Loading Mode and Coating on Dynamic Fatigue of Optical Fiber in Two-Point Bending." Journal of the American Ceramic Society 76, no. 1 (January 1993): 139–44. http://dx.doi.org/10.1111/j.1151-2916.1993.tb03699.x.

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Alves, Elcio Cassimiro, and Luiz Eloy Vaz. "Optimum design of plates structures under random loadings." Rem: Revista Escola de Minas 66, no. 1 (March 2013): 41–47. http://dx.doi.org/10.1590/s0370-44672013000100006.

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Structural optimization problems involving static loading have been studied for some time and in a way these kinds of problems are widely encountered in literature, but problems involving dynamic loading still have few studies not to mention problems involving nondeterministic dynamic loading. This paper presents a formulation of the optimization problem of plates subjected to random loadings. For the modeling of the structure, it used the bending plate element AST6 that explicitly provides these matrices, and dynamic mass reduction and rigidity matrices were used to reduce the computational cost of the problem. . The solution was achieved using the Interior Point Method and the sensitivity analysis of mass, and for the structure's stiffness matrixes the semi-analytical method was used. Three examples are presented to demonstrate the reliability of the process. The first example is an isotropic plate and the other two are problems involving sandwich plates. In all examples, an improved design in respect to the initially proposed geometry was obtained.

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Pang, Miao, Yi Dong, Xing Liu, Wei Sun, and Tiejiong Lou. "Prediction of Structural Behavior of Continuous Reinforced Concrete Beams with Hybrid CFRP-Steel Bars." Materials 15, no. 21 (October 27, 2022): 7542. http://dx.doi.org/10.3390/ma15217542.

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The present investigation aims to identify the flexural performance of two-span concrete beams reinforced with hybrid carbon fiber reinforced polymer (CFRP) and steel bars. By applying a finite element analysis, a comprehensive numerical assessment is performed. The investigated variables are Af/Ar (Af = area of CFRP bars; Ar = total area of CFRP/steel bars), load pattern (symmetrical and unsymmetrical loading) and load type (center-point, third-point and uniform loading). The results show that beams with Af/Ar of 0.25 show 16.0% and 11.3% higher ultimate load at symmetrical and unsymmetrical loading, respectively, than beams with Af/Ar of 0.0 (i.e., beams with steel bars), but the change in ultimate load is not apparent when varying Af/Ar between 0.25 and 1.0. Unsymmetrical loading causes 6.0–15.0% greater deflection capacities than the symmetrical one. When Af/Ar increases from 0.0 to 1.0, moment redistribution at symmetrical loading is decreased significantly by 62%, while the redistribution variation is marginal at unsymmetrical loading. In addition, the applicability of two equations based on the ultimate strain in tensile bars for predicting moment redistribution is evaluated. It is generally shown that these equations can account for the influence of Af/Ar and load type.

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Oh, J., S. M. Yoon, and J. M. Park. "Denitrification in submerged biofilters of concentrated-nitrate wastewater." Water Science and Technology 43, no. 1 (January 1, 2001): 217–23. http://dx.doi.org/10.2166/wst.2001.0051.

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To understand the possibilities and limitations of the treatment of concentrated nitrate in wastewater, a space-saving biofilm process was introduced to investigate how efficiently concentrated nitrate was utilized in a biofilm process. Lab-scale submerged biofilters stuffed with plastic pall-ring media were developed for the treatment of wastewater containing high nitrate concentration. Two identical biofilters were operated at 2 and 4 hr media HRT in parallel and the concentration of nitrate in the influent was increased stepwise from 50 to 3000 mg-N/L. The concentration of NOx in the effluent was measured at various volumetric loading rates that were proportional to influent nitrate concentrations. There was a critical point for volumetric loading rate (9 kg NO3–N/m3/day) distinguishing the biofilter performances. At the volumetric loading rate below this critical point, the effluent NOx concentration was maintained steadily in spite of the drastic change in the loading rates. However, the effluent NOx concentration severely fluctuated for the small change when the loading rate was higher than the critical point. It was found that the reactor performance was closely related with the biomass concentration (g-dw/ring) in the biofilters.

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Califano, America. "Fatigue of Composite Materials Subjected to Variable Loadings." Materials Science Forum 957 (June 2019): 303–10. http://dx.doi.org/10.4028/www.scientific.net/msf.957.303.

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In the present work, a model describing the fatigue behaviour of composite materials under spectrum loading is presented. The approach is based on a two-parameter model describing the strength degradation kinetics for fibre-reinforced materials subjected to cyclic loadings, both with constant and variable amplitudes. The point of strength of the presented approach is that it allows to consider cyclic loadings as they are, without simplifications or reductions. In particular, the analytical background of the model is based on the statements that govern the composites behaviour and focused on the issues related to this class of materials when subjected to fatigue. Then, the final step is the definition of a damage accumulation rule that goes over Miner’s rule unreliability when applied to fibre-reinforced materials. As a matter of fact, it allows to take into account the effects of different loading histories, underlining the importance of the sequence of loads application in the framework of the presented approach.

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Abdul-Latif, A., M. Clavel, V. Ferney, and K. Saanouni. "On the Modeling of Nonproportional Cyclic Plasticity of Waspaloy." Journal of Engineering Materials and Technology 116, no. 1 (January 1, 1994): 35–44. http://dx.doi.org/10.1115/1.2904253.

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The isotropic hardening is known to play an effective role in the overhardening of materials under nonproportional cyclic loading. However, the behavior of the two states of Waspaloy (namely overaged and underaged states) under these loading conditions, shows that the kinematic hardening has also a considerable role in the overhardening. Experimental tests were carried out on these two states under various proportional and nonproportional cyclic loading conditions at room temperature. The effect of loading paths on micro-mechanisms of deformation was studied. From a microstructural point of view, it was shown that the deformation modes (quantitatively and qualitatively) depend on the loading path and the heat treatment. A constitutive model is proposed to describe the effect of overhardening, under the nonproportional loading conditions, on the kinematic hardening. The predicted responses are in good agreement with experimental results.

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T, Srinath, and Shyam Kumar E. "Flexure and bonding behaviour of glass fiber reinforced epoxy resin composite beam under two point loading mechanism." IOSR Journal of Mechanical and Civil Engineering 14, no. 02 (April 2017): 78–84. http://dx.doi.org/10.9790/1684-1402057884.

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., Arjun R. P. Reddy. "STUDIES ON STRENGTH AND DEFORMATION BEHAVIOUR OF TWO-WAY NSC AND HSC SLABS UNDER SINGLE POINT LOADING." International Journal of Research in Engineering and Technology 05, no. 26 (September 25, 2016): 42–46. http://dx.doi.org/10.15623/ijret.2016.0526009.

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Sheng, Xingwang, Weiqi Zheng, and Zhihui Zhu. "Mechanical Behaviors and Fatigue Performances of Ballastless Tracks Laid on Long-Span Cable-Stayed Bridges with Different Arrangements." Sensors 19, no. 19 (September 27, 2019): 4195. http://dx.doi.org/10.3390/s19194195.

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In this paper, we present a new attempt to lay ballastless tracks on long-span cable-stayed bridges on high-speed railways. The arrangements of ballastless tracks laid on cable-stayed bridges can be divided into two conditions: (i) across the cable suspension-point cross-section or (ii) in discontinuity at the cable suspension-point cross-section. At present, there is a lack of in-depth research on ballastless tracks laid on long-span cable-stayed bridges, especially on the mechanical behaviors and fatigue performances of the ballastless tracks with different arrangements. For this paper, a segmental model of a long-span cable-stayed bridge was designed and built, on which full-scale ballastless tracks with two different arrangements were arranged. A series of fatigue tests and post-fatigue loading tests were carried out based on the two selected full-scale ballastless tracks. Some conclusions were drawn as follows. For the longitudinal end of the ballastless track, which is far from the loading positions, the interlayers of the ballastless tracks tend to warp up relatively, and the compressive pressures at the interlayers are also unloaded. However, there is no void or gap formed at the interlayers of the longitudinal end of the track slab due to the precompression of the rubber isolation layer. For the center of the track slab, which is close to the loading positions, the compressive deformations occur at the interlayers, and the pressures at interlayers are also increased. The maximum compressive deformation is less than 0.5 mm under the standard train axle load (170 kN), and it cannot affect the high-speed trains’ operation. With the increase of the post-fatigue loading, the load-displacement curves and the load-pressure variation curves of the ballastless tracks show apparent nonlinearity. Moreover, with the increase of the fatigue loading cycles, the compressive stiffness enhancement or degradation of the ballastless tracks are not noticeable. That is to say, the ballastless tracks laid on the long-span cable-stayed bridges with different arrangements have good mechanical behaviors, and their fatigue performances can also be guaranteed after bearing repeated loadings.

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Hawileh, R., J. A. Abdalla, and Adil K. Al-Tamimi. "Flexural Performance of Strengthened RC Beams with CFRP Laminates Subjected to Cyclic Loading." Key Engineering Materials 471-472 (February 2011): 697–702. http://dx.doi.org/10.4028/www.scientific.net/kem.471-472.697.

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Seismic retrofitting of reinforced concrete (RC) beams by means of carbon fiber reinforced polymer (CFRP) composites is one of the state-of-the-art techniques that have been widely practiced lately. Such external strengthening schemes seem to enhance both stiffness and strength of RC beams when subjected to static and cyclic loading. Extensive research investigation has been carried out for beams subjected to monotonic static loading while limited research data is available for beams subjected to cyclic loadings. Therefore, this study is initiated and its aim is to present the results of full scale experimental testing of RC beams under four-point-bending loading and subjected to monotonic and cyclic loading histories up to failure of the specimens. An unstrengthened RC beam was tested monotonically to serve as a bench-mark. The remaining two externally strengthened RC beams with different anchorage schemes were tested under cyclic loading. The strengthening test matrix included beams bonded with a unidirectional CFRP plate that covers 90% of the beam's soffit length, with one or two unidirectional layers of CFRP wraps at anchorage locations along the beam's length. The anchorage locations were at the edges of the CFRP plate and at the middle of the beam's span. The results presented herein show an increase in the overall strength for the strengthened beams over the unstrengthened ones. The different failure modes and the resulting ductility of the tested specimens are also discussed. This study is considered to be the first part of an extensive program that aims to investigate the different parameters that govern the external strengthening techniques of RC beams when subjected to cyclic loading.

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Vavro, Leona, Martin Vavro, Kamil Soucek, Tomás Fíla, Petr Koudelka, Daniel Vavrík, and Daniel Kytýr. "Study of fracture processes in sandstone subjected to four-point bending by means of 4D X-ray computed micro-tomography." ACTA IMEKO 11, no. 2 (May 4, 2022): 1. http://dx.doi.org/10.21014/acta_imeko.v11i2.1220.

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<p class="Abstract">High-resolution X-ray computed micro-tomography (CT) is a powerful technique for studying the processes of crack propagation in non-homogenous quasi-brittle materials such as rocks. To obtain all the significant information about the deformation behaviour and fracture characteristics of the studied rocks, the use of a highly specialised loading device suitable for the integration into existing tomographic setups is crucial. Since no adequate commercial solution is currently available, a completely newly-designed loading device with a four-point bending setup and vertically-oriented scanned samples was used. This design of the loading procedure, coupled with the high stiffness of the loading frame, allows the loading process to be interrupted at any time and for CT scanning to be performed without the risk of the sudden destruction of the scanned sample.</p>This article deals with the use of the 4D CT for the visualisation of crack initiation and propagation in clastic sedimentary rocks. Two types of quartz-rich sandstones of Czech provenance were used for tomographic observations during the four-point bending loading performed on chevron notched test specimens. It was found that the crack begins to propagate from the moment that ca. 80 % of the maximum loading force is applied.

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Han, Shou Hong, Zhen Hua Lu, and Yong Jin Liu. "Study on Multi-Axial Mechanical Properties of a Polyurethane Foam and Experimental Verification." Advanced Materials Research 311-313 (August 2011): 301–8. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.301.

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In order to investigate the multi-axial mechanical properties of a kind of PU (polyurethane) foam, some experiments in different loading conditions including uni-axial tension, uni-axial compression, hydrostatic compression and three-point bending were conducted. It is shown that the hydrostatic component influences yield behavior of PU foam, the yield strength and degree of strain hardening in hydrostatic compression exceed those for uni-axial compression. In terms of the differential hardening constitutive model, the evolution of PU foam yield surface and plastic hardening laws were fitted from experimental data. A finite element method was applied to analyze the quasi-static responses of the PU foam sandwich beam subjected to three-point bending, and good agreement was observed between experimental load-displacement responses and computational predictions, which validated the multi-axial loading methods and stress-strain constitutive model parameters. Moreover, effects of two foam models applied to uni-axial loading and multi-axial loading conditions were analyzed and compared with three-point bending tests and simulations. It is found that the multi-axial constitutive model can bring more accurate prediction whose parameters are obtained from the tests above mentioned.

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Singh, Neetu, Rajesh Kumar Vishwakarma, U. S. Shivhare, Santanu Basu, and G. S. Vijaya Raghavan. "Effect of Moisture Content and Orientation on Force-Deformation Behavior of Pigeon Pea Grains during Uniaxial Compression." Transactions of the ASABE 60, no. 3 (2017): 989–97. http://dx.doi.org/10.13031/trans.12070.

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Abstract. The force-deformation behavior of pigeon pea grains and its correlation with moisture content was studied. Hertz’s theory of contact stresses was applied to predict the splitting and failure of cotyledons during uni-axial compressive loading between two rigid parallel plates. The apparent modulus of elasticity of pigeon pea decreased from 280.52 to 9.29 MPa when force was applied normal to the hilum joint (horizontal loading), whereas it decreased from 208.08 to 33.37 MPa when force was applied in the direction of the hilum joint (vertical loading) with an increase in moisture content from 5.28% to 34.568% (d.b.). At higher moisture contents (15.17% and above), the grains yielded after considerable deformation, thus showing a change in nature from brittle to ductile. Distribution of stresses below the point of contact were calculated and plotted to predict the location of the critical point, which was found at 0.45 to 0.75 mm and at 0.50 to 0.67 mm below the contact point in vertical and horizontal loading, respectively, depending on moisture content. The bio-yield of pigeon pea grains was due to breakage of the cotyledons in horizontal loading, whereas it was due to separation of the cotyledons in vertical loading. Separation of the cotyledons from each other was initiated before yielding of the cotyledons at lower moisture contents, and thus splitting of the seed took place. Keywords: Contact stresses, Hertz theory, Mechanical properties, Pigeon peas, Splitting.

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Putra, I. kadek Ardi, I. Wayan Budiarsa Suyasa, and I. G. B. Sila Dharma. "PENETAPAN DAYA TAMPUNG BEBAN PENCEMAR TUKAD MATI DI KABUPATEN BADUNG DENGAN MODEL QUAL2KW 5.1." ECOTROPHIC : Jurnal Ilmu Lingkungan (Journal of Environmental Science) 11, no. 2 (November 30, 2017): 87. http://dx.doi.org/10.24843/ejes.2017.v11.i02.p11.

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ABSTRAK Tukad Mati is one of watershed that is flow through two regencies of Badung and Denpasar that has 12 km length. Tukad Mati functioned as irrigation, drainage system and as the exile of wastewater from all activities along the river. Because of the pollution, the water quality has degraded. The source of pollution is organic matter pollutant, agricultural pollutant such as pesticide and hazardous waste. The aim of this research is knowing the pollutant loading rate from point source and non point source using Qual2kw model, to define that amount of pollutant that are allowed to exile in Tukad Mati river. The water quality parameter that analyzed is DO, COD, BOD and Phosphate. This research divided into three sections, and 4 scenario of simulation to know allowed loading rate of pollutant along the river. The result of simulation using Qual2kw for BOD that is the minimum DO loading rate was 1,15 kg/day for section 1 then maximum loading rate is 64,88 kg/day on section 3. Meanwhile for COD parameter, the minimum loading rate is 1446,61 kg/day and in the upstream the minimum COD loading rate 1375,06 kg/day. For phosphate parameter the loading rate that allowed is 0,79 kg/day, while in the upstream maximum 12,57 kg/day on segment 3. Keywrods : Tukad Mati, Qual2KW 5.1, Loading Rate, water quality

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Fernandes, Jorge Cruz, Vera Pires, Pedro M. Amaral, and Luís Guerra Rosa. "Analysis of Strength Scaling Effect in Portuguese Limestone: Comparison between Three- and Four-Point Bending Tests." Materials Science Forum 636-637 (January 2010): 1336–41. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.1336.

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This paper presents a comparative study between 3- and 4-point bending tests applied to five Portuguese limestones. The study has been conducted on sawed limestone specimens, all showing the same surface finishing. The materials were compared for two distinct situations: i) using a 3-point flexure loading configuration in batches of materials with larger cross sectional specimen dimension (50 × 30 mm2); and ii) using a 4-point flexure loading configuration in the same batch of materials but with smaller cross sectional dimensions (30 × 25 mm2). In all situations, the materials have broken due to intrinsic volume defects. Formulae for the effective volumes and effective surfaces for rectangular beam specimens loaded in flexure were reviewed in order to analyse the strength scaling effect. The results show the applicability of the Weibull statistics to explain the differences in the results of the 3-point and 4-point bending tests, even when different cross sectional sizes are employed. Among other important remarks, in all the different limestone specimens used it was possible to confirm that the strength values determined experimentally via 3-point bending are of the same order as those estimated for the same loading configuration but via experimental data of 4-point bending tests using the Weibull strength scaling approach, even if employing a different cross-sectional dimension.

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Adkins, Bruce D., Jill B. Heink, and Burtron H. Davis. "Comparison of Nitrogen Adsorption and Mercury Penetration Results. Pore Size Distributions for a Series of Mo-A12O3 Catalysis with Increasing MoO3 Content." Adsorption Science & Technology 4, no. 1-2 (March 1987): 87–104. http://dx.doi.org/10.1177/0263617487004001-208.

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Scanning electron microscopic data, X-ray diffraction patterns and porosity measurements are consistent with a structure for an Mo-A12O3 catalyst series containing a single surface layer of Mo up to the point where the Mo loadings exceed the amount required for a monolayer. For greater Mo loadings than required for a monolayer, three dimensional orthorhombic MoO3 is also present. The cumulative pore volume, on an alumina basis, does not appear to be significantly altered by MoO3 loadings up to about 15 wt.%. The BET surface area, on an alumina basis, remains constant with Mo loading. However, the apparent surface area calculated from mercury penetration data decreases with Mo loading. For these materials with cylindrical pores, the Broekhoff-deBoer model for the calculation of pore size distributions produced closer agreement to the mercury penetration pore size distribution. This is in contrast to materials composed of nonporous spheres where the Broekhoff-deBoer model provided poorer agreement to mercury penetration results than either the Cohan or a packed sphere model. The results show that, within a factor of two the pore size distributions calculated from nitrogen adsorption and mercury penetration data are comparable.

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Li, Xiangyu, Fugang Li, Minzu Liang, Kefan Zhang, and Zhandong Tian. "Research on Dynamic Constitutive Model and Fracture Characteristics of Two High Strength Steels." Journal of Physics: Conference Series 2168, no. 1 (January 1, 2022): 012016. http://dx.doi.org/10.1088/1742-6596/2168/1/012016.

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Abstract 58SiMn and 50SiMnVB are commonly used shell materials in bombs, and their dynamic constitutive model and fracture properties directly determine the mass distribution of the bomb. Tensile tests were carried out on two high-strength steels, and the parameters of the yield point, tensile strength and plastic failure strain as well as the John-Cook model were determined. The fracture morphologies of the two steels in the quasi-static tension and in the dynamic tension were analyzed. The research results show that the yield strength of 58SiMn steel remains unchanged with increasing strain rate. The yield strength and tensile strength of 50SiMnVB increase as the rate of elongation increases, and the ability to plastically deform decreases, which shows the properties of embrittlement under high speed loading. With the same elongation rate, 50SiMnVB steel has higher strength and toughness. 58SiMn steel is a tensile brittle fracture from a macroscopic point of view and a quasi-split fracture from a microscopic point of view; 50SiMnVB steel is a mixed lap shear fracture under axial tensile load. With increasing loading rate, the tensile fracture tends to pure shear fracture.

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Wolff, Jonas O., and Marie E. Herberstein. "Three-dimensional printing spiders: back-and-forth glue application yields silk anchorages with high pull-off resistance under varying loading situations." Journal of The Royal Society Interface 14, no. 127 (February 2017): 20160783. http://dx.doi.org/10.1098/rsif.2016.0783.

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The anchorage of structures is a crucial element of construction, both for humans and animals. Spiders use adhesive plaques to attach silk threads to substrates. Both biological and artificial adhesive structures usually have an optimal loading angle, and are prone to varying loading situations. Silk anchorages, however, must cope with loading in highly variable directions. Here we show that the detachment forces of thread anchorages of orb-web spiders are highly robust against pulling in different directions. This is gained by a two-step back-and-forth spinning pattern during the rapid production of the adhesive plaque, which shifts the thread insertion point towards the plaque centre and forms a flexible tree root-like network of branching fibres around the loading point. Using a morphometric approach and a tape-and-thread model we show that neither area, nor width of the plaque, but the shift of the loading point towards the plaque centre has the highest effect on pull-off resistance. This is explained by a circular propagation of the delamination crack with a low peeling angle. We further show that silken attachment discs are highly directional and adjusted to provide maximal performance in the upstream dragline. These results show that the way the glue is applied, crucially enhances the toughness of the anchorage without the need of additional material intake. This work is a starting point to study the evolution of tough and universal thread anchorages among spiders, and to develop bioinspired ‘instant’ anchorages of thread- and cable-like structures to a broad bandwidth of substrates.

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Torabi, A. R., and Behnam Saboori. "Experimental and theoretical investigation of mixed mode I/III brittle fracture of U-notched polystyrene components." Journal of Strain Analysis for Engineering Design 53, no. 1 (November 12, 2017): 15–25. http://dx.doi.org/10.1177/0309324717739725.

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Brittle fracture of components made of the general-purpose polystyrene and weakened by an edge U-notch under combined tension/out-of-plane shear loading conditions (mixed mode I/III) has not been studied yet experimentally or theoretically. In this research, a recently developed loading fixture is employed for experimentally investigating the fracture of U-notched general-purpose polystyrene samples with various notch tip radii of 0.5, 1, 2 and 4 mm when they are subjected to different combinations of tension/out-of-plane shear. The samples are fabricated with four different notch tip radii with the purpose of assessing the influence of this geometrical parameter. The experimental values of fracture load and out-of-plane fracture angle are theoretically predicted by the two stress-based criteria of point stress and mean stress lately extended to general loading case of mixed mode I/II/III. It is shown that both the point stress and mean stress criteria provide acceptable predictions to fracture behavior of U-notched general-purpose polystyrene specimens. The critical distances needed for the point stress and mean stress criteria are determined based on the experimental results of the U-notched samples tested under pure mode I loading. No meaningful difference is found between the fracture loads and fracture initiation angles predicted by the point stress and mean stress criteria. It is also observed that as the mode III contribution in the applied mixed mode I/III loading increases, a larger total external load is needed for the fracture of U-notched general-purpose polystyrene specimens to occur.

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Bert, C. W. "Improved Equation for Shear Modulus Using Four-Point Ring-Twist Test Data." Journal of Thermoplastic Composite Materials 14, no. 6 (November 2001): 489–97. http://dx.doi.org/10.1106/gng0-lr9b-ffkb-rv13.

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There are numerous test-specimen configurations for determining the static shear modulus of composites. Selection of specimen configuration depends primarily on product component configuration. Two-ring specimens in use are the split-ring twist specimen and the four-point-loading ring-twist specimen. The latter is more advantageous, since it uses an intact ring. However, reported validation tests on aluminum rings showed a large error in predicted shear modulus. The present paper provides an improved analysis that takes into account the tilting of the cross section on the loading bar.

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Elkelish, M. S., and Hugh Robinson. "Longitudinal cracking of composite beams with ribbed metal deck." Canadian Journal of Civil Engineering 13, no. 6 (December 1, 1986): 733–40. http://dx.doi.org/10.1139/l86-108.

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An analytical study of the longitudinal cracking of composite beams with ribbed concrete slab on metal deck is presented. A layered finite element is used to model the composite beam in the analysis. The influence of six parameters on the development of the longitudinal crack is investigated in this study. These parameters are type of loading, compressive strength of the concrete slab, beam span to slab width ratio, thickness of the solid part of the slab, percentage of transverse reinforcement, and the existence of the metal deck. Three types of loading are considered, namely, uniformly distributed load over the entire slab area, single point load applied at mid-span of the beam, and two point loads applied at the third points of the span. The type of loading of composite beams has a significant effect on the location of the initial longitudinal crack.

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Ishikawa, Tatsuya, Etsuo Sekine, and Seiichi Miura. "Cyclic deformation of granular material subjected to moving-wheel loads." Canadian Geotechnical Journal 48, no. 5 (May 2011): 691–703. http://dx.doi.org/10.1139/t10-099.

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This paper describes a new testing method to examine the mechanical behavior of railroad ballast subjected to repeated train passages on ballasted track. Two types of cyclic loading tests, namely a single-point loading test and a moving-wheel loading test, were performed with small-scale models of ballasted track. Next, a “multi-ring shear apparatus” was developed as a type of torsional simple shear apparatus, and the applicability of a newly proposed multi-ring shear test to an element test of railroad ballast subjected to moving-wheel loads was examined by comparing the results of multi-ring shear tests with those of small-scale model tests. As a result, it was recognized that cumulative strain obtained from multi-ring shear tests is almost equivalent to the one derived from small-scale model tests. Moreover, it was revealed that the difference between loading methods has a considerable influence on the cyclic plastic deformation of railroad ballast because settlement in a moving-wheel loading test was much larger than the one in a single-point loading test. These results lead to the conclusion that a multi-ring shear test has an excellent applicability to the estimation of deformation behavior of granular materials subjected to moving-wheel loads.

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Battista, F., J. P. Mollicone, P. Gualtieri, R. Messina, and C. M. Casciola. "Exact regularised point particle (ERPP) method for particle-laden wall-bounded flows in the two-way coupling regime." Journal of Fluid Mechanics 878 (September 10, 2019): 420–44. http://dx.doi.org/10.1017/jfm.2019.622.

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The exact regularised point particle (ERPP) method is extended to treat the inter-phase momentum coupling between particles and fluid in the presence of walls by accounting for vorticity generation due to particles close to solid boundaries. The ERPP method overcomes the limitations of other methods by allowing the simulation of an extensive parameter space (Stokes number, mass loading, particle-to-fluid density ratio and Reynolds number) and of particle spatial distributions that are uneven (few particles per computational cell). The enhanced ERPP method is explained in detail and validated by considering the global impulse balance. In conditions when particles are located close to the wall, a common scenario in wall-bounded turbulent flows, the main contribution to the total impulse arises from the particle-induced vorticity at the solid boundary. The method is applied to direct numerical simulations of particle-laden turbulent pipe flow in the two-way coupling regime to address turbulence modulation. The effects of the mass loading, the Stokes number and the particle-to-fluid density ratio are investigated. The drag is either unaltered or increased by the particles with respect to the uncoupled case. No drag reduction is found in the parameter space considered. The momentum stress budget, which includes an extra stress contribution by the particles, provides the rationale behind the drag behaviour. The extra stress produces a momentum flux towards the wall that strongly modifies the viscous stress, the culprit of drag at solid boundaries.

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Zhang, Lu, Jie Jin, Wei Zhou, Wen-Liang Li, and Meng Qiao. "A Nonlinear Fatigue Damage Model Based on Equivalent Transformation of Stress." Journal of Engineering 2021 (November 9, 2021): 1–8. http://dx.doi.org/10.1155/2021/5581307.

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It is rather difficult for engineers to apply many of the fatigue damage models for requiring a knee point, material-dependent coefficient, or extensive testing, and some of them are only validated by a fatigue test of two-stage loading rather than higher-stage loading. In this paper, we propose a new model of fatigue cumulative damage in variable amplitude loading, which just requires the information of the S-N curve determined from the fatigue experiment. Specifically, the proposed model defines a stress equivalent transformation way to translate the damage of one stress to another stress through simple calculation. Experimental data of fatigue including two-, three-, and four-block loading verify the superiority of the proposed model by comparing it with the Miner model and Manson model. The results show that the proposed model can be generalized to any type of loading and presents a better prediction. Therefore, the advantage of the proposed model can be easily used by an engineer.

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Fincato, Riccardo, and Seiichiro Tsutsumi. "A numerical study of the return mapping application for the subloading surface model." Engineering Computations 35, no. 3 (May 8, 2018): 1314–43. http://dx.doi.org/10.1108/ec-12-2016-0446.

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Purpose Many practical problems in engineering require fast, accurate numerical results. In particular, in cyclic plasticity or fatigue simulations, the high number of loading cycles increases the computation effort and time. The purpose of this study is to show that the return mapping technique in the framework of unconventional plasticity theories is a good compromise between efficiency and accuracy in finite element analyses. Design/methodology/approach The accuracy of the closest point projection method and the cutting plane method implementations for the subloading surface model are discussed under different loading conditions by analyzing the error as a function of the input step size and the efficiency of the algorithms. Findings Monotonic tests show that the two different implicit integration schemes have the same accuracy and are in good agreement with the solution obtained using an explicit forward Euler scheme, even for large input steps. However, the closest point projection method seems to describe better the evolution of the similarity centre in the cyclic loading analyses. Practical implications The purpose of this work is to show two alternative implicit integration schemes of the extended subloading surface method for metallic materials. The backward Euler integrations can guarantee a good description of the material behaviour and, at the same time, reduce the computational cost. This aspect is particularly important in the field of low or high cycle fatigue, because of the large number of cycles involved. Originality/value A detailed description of both the cutting plane and closest point projection methods is offered in this work. In particular, the two integrations schemes are compared in terms of accuracy and computation time for monotonic and cyclic loading tests.

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Ohi, Kenichi, and Jae Hyouk Choi. "An Adaptive Loading Test on Collapse Mechanism Formation of Multi-Story Steel Frames Subjected to Uncertain Lateral Load Pattern." Key Engineering Materials 345-346 (August 2007): 1169–72. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.1169.

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An adaptive loading system is developed to examine a design point of multi-story steel test frames subjected to uncertain load pattern. Lateral loads are given as a random combination of basic load patterns, and the system drives a test frame to the most likely failure situation. Two-story steel moment resisting frames are tested considering a failure mechanism formation of plastic collapse as a tentative limit state. A random 2-dof lateral force is given by a random combination of two basic load patterns, which are arranged to represent elastic earthquake load effects. Hybrid design point search or adaptive loading tests on the 2-story frame are performed, and the detected likely failure mechanisms are compared with the results of pseudo-dynamic response tests to deterministic excitations.

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van den Horn, G. J., N. Westerhof, and G. Elzinga. "Feline left ventricle does not always operate at optimum power output." American Journal of Physiology-Heart and Circulatory Physiology 250, no. 6 (June 1, 1986): H961—H967. http://dx.doi.org/10.1152/ajpheart.1986.250.6.h961.

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In a previous study we showed that under a variety of conditions the feline left ventricle operates at optimum external power. This condition was defined as matching. In the present study matching of left ventricle and systemic arterial tree has been further investigated in the open-thorax cat during control, after volume loading (n = 8), and during norepinephrine infusion (n = 8). The pump-function graph relating mean left ventricular pressure and mean flow was fitted with a parabola characterized by two parameters, the pressure axis and the flow axis intercepts (Pmax and Fmax, respectively). After volume loading, as well as during norepinephrine infusion, the pump-function graph showed an outward shift plus a clockwise rotation. Pmax and Fmax increased 27 and 8% during volume loading and 37 and 8% during norepinephrine. In the steady states the mean flows at the working point and at the point of optimum external power were determined. During control and volume loading these flow values could not be shown to differ. However, during norepinephrine infusion, flow at the working point was found to be smaller than at optimal external power. This finding implies that during norepinephrine, the left heart does not operate at optimum external power; so a mismatch of heart and periphery is obtained.

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Chen, Shui Fu, and Ying Gong. "Pushover Analysis of Light-Weight Steel Portal Frame Structures under Strong Wind Loading." Advanced Materials Research 446-449 (January 2012): 386–89. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.386.

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An elastic-plastic pushover analysis has been performed to a typical two-bay light-weight steel portal frame for investigation of the nonlinear load-deformation behaviors of the structure under strong wind loading. The finite-element model is first established for the portal frame. Then the monotonically increased lateral load and uniformly distributed vertical load representing wind loading are applied to the frame while the structure deforms from full elastic range to elastic-plastic stage. The loading process continues until the top displacement reaches its target value or enough number of plastic hinges occurs so that the structure changes to an unstable mechanism. The analysis results indicate that different lateral loading modes (top point loading or uniformly distributed loading) lead to almost the same deformation and failure behavior of the frame, and the final load-carrying capacity of the frame considerably decreases with increase of the vertical loading.

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Kunecký, Jiří, Václav Sebera, Jan Tippner, Hana Hasníková, Michal Kloiber, Anna Arciszewska-Kędzior, and Jaromír Milch. "Mechanical Performance and Contact Zone of Timber Joint With Oblique Faces." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 63, no. 4 (2015): 1153–59. http://dx.doi.org/10.11118/actaun201563041153.

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The goal of the work was to evaluate mechanical performance of full-scale timber beams containing scarf joint with a dowel. Work focused on standard testing using modular system to obtain effective stiffness and strength of the beams with and without the joint. The work further researched a contact zone between two timber parts of the joint – at the scarf face. This was carried out using non-destructive optical technique – digital image correlation (DIC) and newly developed algorithm. The joint was made of Norway spruce, dims. 6×0.2×0.24 m and was loaded by two modes: a) 3-point bending and b) 4-point bending. During the loading, a sequence of images was acquired for further investigation of contact zone using the proposed algorithm. The joint with scarf and dowel provided enough effective stiffness, ie. 73–93% for 3-point bending test and 71% for 4-point bending with respect to MOE measured on reference solid beams. Effective strength of the joint was also relatively high and in a range of 55% and 60% with respect to reference solid beams in both 3-point and 4-point bending tests. Contact length differed for loading modes. Mean contact length in symmetrical 4-point bending was about 40%, for asymmetrical 3-point bending test, it was approx. 20% on face closer to support and 44% on a face closer to loads.

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Yoshida, H., T. Ogasa, and M. Uemura. "Local Stress Distribution in the Vicinity of Loading Points in Flexural Test of Orthotropic Beams." Journal of Energy Resources Technology 113, no. 4 (December 1, 1991): 230–34. http://dx.doi.org/10.1115/1.2905905.

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The two-dimensional stress distributions in orthotopic composite beam under 4-point flexure are analyzed by replacing the concentrated load by distributing pressure in the vicinity of loading nose and by expanding the stress function for compatability equation in terms of Fourier series. The validity of analytical results is verified experimentally by using the photoelastic film-coating technique on unidirectional reinforced plastics. It is shown that the local stress distributions around the loading points are complicated and are very different from those predicted by elementary beam theory; and hence, the reliability of flexural strength and interlaminar shear strength defined by elementary beam theory are in question. It is suggested that the 4-point flexure is reasonable and recommendable as a standard testing method compared with the 3-point flexural one.

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Baleri, M., F. Sassani, and P. L. Ko. "Stick-Slip Vibration Between Two Large Concentric Circular Discs in Rotational Contact With Multiple Point Loads." Journal of Mechanical Design 125, no. 4 (December 1, 2003): 786–92. http://dx.doi.org/10.1115/1.1631572.

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This paper presents a study of the stick-slip frictional phenomenon when large contact areas subjected to uneven contact loads, such as the rotating platform of excavators and large robotic manipulators, are involved. The objective of the investigation is to a gain better understanding of the phenomenon from experimental observations and to develop a mathematical representation that can be used for modeling, simulation and design purposes. A dynamic integral-model has been proposed and simulations have been carried out. The effects of various system parameters on the behavior of the system have been studied experimentally and analytically. The simulation results using the proposed integral-model are in good agreement with the experimental results. The latter also show that stick-slip vibrations can be influenced by the loading conditions.

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Gilmore, K. R., K. J. Husovitz, T. Holst, and N. G. Love. "Influence of organic and ammonia loading on nitrifier activity and nitrification performance for a two-stage biological aerated filter system." Water Science and Technology 39, no. 7 (April 1, 1999): 227–34. http://dx.doi.org/10.2166/wst.1999.0363.

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A pilot-scale, two-stage (carbon oxidation stage one, ammonia oxidation stage two) fixed film biological aerated filter (BAF) process was operated during the wintertime on-site at a domestic wastewater treatment plant. Over the study period, hydraulic loadings to the system were varied and generated a range of organic and ammonia loading conditions. Nitrification performance was monitored based on water quality along the length of the filters, effluent water quality, and activity levels of ammonia-oxidizing bacteria within the biofilm using an oligonucleotide probe. Overall nitrification efficiency for wintertime conditions (average temperature 12.4 ± 0.1°C) was greater than 90 percent when ammonia-N loadings to the second stage were 0.6 kg/m3-day or less. Nitrification efficiency started to deteriorate at loadings beyond this point. Biofilm and liquid samples were collected along the distance of the two columns at high and low ammonia loadings. The degree of activity observed by ammonia oxidizing bacteria in the biofilm corresponded with the disappearance of ammonia and the generation of nitrate as water passed through the columns. The zones of ammonia oxidizing activity progressed along the length of the columns as organic and ammonia loadings to the system increased. The oligonucleotide probe data suggest that this shift in the location of the nitrifier population is due to higher BOD loads to the second stage, which supported higher levels of heterotrophic growth in the column.

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Journal articles on the topic 'Two-point loading'

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